1. Field of the Invention
This invention relates to a binocular in which an interpupillary adjustment is carried out by a biaxial interlock mechanism.
2. Description of the Related Art
Conventionally, there is known a type of binocular which has an interpupillary adjustment function. The distance between the eyes of different users of binoculars varies. By carrying out the interpupillary adjustment function, a distance between optical axes of a pair of eyepieces can be adjusted so as to suit for the distance between the eyes of any user. There are two types of interpupillary adjustment function. One is a uniaxial type, and the other is a biaxial type.
In the uniaxial type binocular, each of a pair of telescopic optical systems is respectively rotated around an axis, which is parallel to optical axes of the telescopic optical systems and is equal distant from each telescopic optical system. Namely, there is one axis for rotation of the telescopic optical systems in order to adjust the distance between the optical axes of the telescopic optical systems. In the biaxial type binocular, the telescopic optical systems have respective Porro prisms as erector prismatic systems, respective objective optical systems and respective eyepieces whose optical axes are displaced out of alignment with those of the objective optical systems. Each of a pair of eyepieces and Porro prisms are respectively rotated around an optical axis of a corresponding objective optical system and the rotations of the eyepieces are interlocked. Namely, there are two axes of rotation of the eyepieces for adjusting the distance between the optical axes of the eyepieces.
In the biaxial type binocular, the objective optical systems are free of the rotation of the eyepieces at all times. Thus, holding members which hold the objective optical systems and holding members which hold the eyepieces are respectively supported by different supporting members.
In a manufacturing process of binoculars, operations such as centering of the optical axis and an adjustment of direction of optical axes are performed, with respect to optical axes of left and right telescopic optical systems. The centering of the optical axis is a process by which an optical axis of an eyepiece and an optical axis of an objective optical system become coaxial in each of the left and right telescopic optical systems. The adjustment of direction of optical axes is a process by which optical axes of the left and right telescopic optical systems become parallel. These processes are carried out, after the objective optical systems and the eyepieces are respectively mounted on the holding members, for example the lens barrels, and the holding members are assembled.
As described above, in the biaxial binocular, the holding members of the eyepieces with Porro prisms and the objective optical systems are respectively supported by different supporting members. With respect to each of the left and right telescopic optical systems, the manner in which the objective optical system and the eyepiece are held in their holding members should be adjusted such that the above-mentioned centering is achieved. Also, the angular relationship between the holding members should be adjusted so that the optical axes of the left and right telescopic optical systems are parallel. Namely, the adjustment of the positional relationship between the holding members, and the alignment of the positions of,the eyepieces and the objective optical systems in the holding members, are achieved simultaneously.
However, a degree of disagreement of the optical axes of the objective lens and the eyepiece subtly varies with each product. Also, the optical axes of the left and right telescopic optical systems are not parallel, subtly varying with each product. As a result, in the manufacturing process of the biaxial type binoculars the above-mentioned adjustments are difficult to achieve requiring a great deal of labor and cost.
Therefore, an object of the present invention is to provide a biaxial type binocular in which the adjustment of optical axes is facilitated in the manufacturing process.
In accordance with an aspect of the present invention, there is provided a binocular, in which an interpupillary distance is adjusted by rotating each of a pair of eyepieces around corresponding optical axis of optical axes of a pair of objective optical systems, comprising: a pair of rotating members that are rotatable for an interpupillary adjustment, each of the rotating members holding a corresponding eyepiece of the pair of eyepieces; and a mounting base. The mounting base includes a rotating member holding portion that holds the pair of rotating members; an objective optical systems holding portion that holds the pair of objective optical systems; and a connecting portion that is unitarily formed with the rotating member holding portion and the objective optical systems holding portion, connecting the rotating member holding portion and the objective optical systems holding portion such that the rotating member holding portion and the objective optical systems holding portion are parallel.
The rotating member holding portion and the objective optical systems holding portion are a flat board-shaped member.
First openings are formed in the rotating member holding portion. Each of the rotating members is mounted in each of the first openings.
Second openings are formed in the objective optical systems holding portion. Each of the objective optical systems is mounted in each of the second openings.
The first openings and the second openings are formed such that: an axis line, perpendicular to the rotating member holding portion, on which a geometric center of gravity of one first opening of the first openings lies, an axis line, perpendicular to the objective optical systems holding portion, on which a geometric center of gravity of one second opening of the second openings corresponding to the one first opening lies, and an optical axis of one objective optical system of the objective optical systems which is mounted in the one second opening, are coincident; and an axis line, perpendicular to the rotating member holding portion, on which a geometric center of gravity of another first opening of the first openings, an axis line, perpendicular to the objective optical systems holding portion, on which a geometric center of gravity of another second opening of the second openings corresponding to the another first opening, and an optical axis of another objective optical system of the objective optical systems, which is mounted in the another second opening, are coincident.
Preferably, the connecting portion is a flat board-shaped member, which is parallel to a plane perpendicular to the rotation member holding portion and the objective optical systems holding portion.
Preferably, the first openings and the second openings are circularly formed.
Optionally, a radius of the first openings is shorter than a radius of the second openings.
Preferably, movable optical systems are provided in a space between the rotating member holding portion and the objective optical systems holding portion. The movable optical systems are disposed on the connecting portion.
Optionally, the movable optical systems are correcting optical systems which correct a focused image tremble. The movable optical systems is two-dimensionally driven on a plane which is perpendicular to the optical axes thereof.
Optionally, a sectional shape of the mounting base, which is taken along a plane perpendicular to the rotating member holding portion and the objective optical systems holding portion, is almost U-shaped.
In accordance with another aspect of the present invention, there is provided a binocular, which includes a right telescopic optical system and a left telescopic optical system, comprising: a right rotating member that holds a right eyepiece group of the right telescopic optical system and is rotatable around a right optical axis of a right objective system of the right telescopic optical system; a left rotating member that holds a left eyepiece group of the left telescopic optical system and is rotatable around a left optical axis of a left objective system of the left telescopic optical system; and a mounting base that includes a first board holding the right rotating member and the left rotating member, a second board holding the right objective optical system and the left objective optical system, and a third board which is unitarily formed with the first board and the second board and connects the first board and the second board such that the first board and the second board are parallel.
The first board is provided with first circular holes in which the right rotating member and the left rotating member are respectively mounted.
The second board is provide with second circular holes in which the right objective optical system and the left objective optical system are mounted.
The rotational movements of the right rotating member and the left rotating member are interlocked.
A straight line, connecting a center of one of the first circular holes, in which the right rotating member is mounted, and a center of one of the second circular holes, in which the right objective optical system is mounted, is coaxial with the right optical axis; and a straight line, connecting a center of another of the first circular holes, in which the left rotating member is mounted, and a center of another of the second circular holes, in which the left objective optical system is mounted, is coaxial with the left optical axis.
Preferably, the third board is perpendicular to the first board and the second board.
Optionally, a radius of the first circular holes is shorter than a radius of the second circular holes.
Preferably, movable optical systems are provided in a space between the first board and the second board. The movable optical systems are disposed on the third board.
Optionally, the movable optical systems are correcting optical systems which correct a focused image tremble. The movable optical systems are two-dimensionally driven on a plane which is perpendicular to the optical axes thereof.
Preferably, a sectional shape of the mounting base, which is taken along a plane perpendicular to the first board and the second board, is almost U-shaped.
In accordance with another aspect of the present invention, there is provided a method for manufacturing binoculars. The binocular comprises a pair of rotating members that is rotatable for an interpupillary adjustment, and a mounting base.
Each of the rotating members holds a corresponding eyepiece of a pair of eyepieces.
The mounting base includes: a rotating member holding portion that holds the pair of rotating members; an objective optical systems holding portion that holds a pair of objective optical systems; a connecting portion that is unitarily formed with the rotating member holding portion and the objective optical systems holding portion, connecting the rotating member holding portion and the objective optical systems holding portion, such that the rotating member holding portion and the objective optical systems holding portion are parallel. The rotating member holding portion and the objective optical systems holding portion are flat board-shaped members.
The method comprises: a first step of forming openings, in which the pair of objective optical systems is mounted, in the objective optical systems holding portion, by abutting a cutting tool against a surface of the objective optical systems holding portion, while rotating the mounting base around a predetermined axis, the cutting tool being positioned from the predetermined axis by a first distance; and a second step of forming openings, in which the pair of rotating members is mounted, in the rotating member holding portion, by abutting the cutting tool against a surface of the rotating member holding portion while rotating the mounting base around the predetermined axis in a similar condition to the first step, the cutting tool being positioned from the predetermined axis by a second distance.
Preferably, the first distance is greater than the second distance.
In accordance with another aspect of the present invention, there is provide another method for manufacturing binoculars. The binocular comprises: a pair of rotating members that is rotatable for an interpupillary adjustment, each of the rotating members holding a corresponding eyepiece of a pair of eyepieces; and a mounting base. The mounting base includes: a first board-shaped portion that holds the pair of rotating members; a second board-shaped portion that holds a pair of objective optical systems; and a connecting portion that is unitarily formed with the first board-shaped portion and the second board-shaped portion, connecting the first board-shaped portion and the second board-shaped portion, such that the first board-shaped portion and the second board-shaped portion are parallel.
The method comprises: a first step of forming first opening, in one portion of the first board-shaped portion and the second board-shaped portion, by abutting a cutting tool against a surface of the one portion while rotating the mounting base around a predetermined axis; and a second step of forming second opening which is smaller than the first opening, in another portion of the first board-shaped portion and the second board-shaped portion, by abutting the cutting tool against a surface of the another portion while rotating the mounting base around the predetermined axis in a similar condition to the first step.
According to the present invention, the pair of objective optical systems and the pair of rotating members which hold the pair of eyepieces are mounted in a single mounting base. Further, in the left and right telescopic optical systems, the opening in which the rotating member is mounted and the opening in which the objective optical system is mounted are formed such that the axis of the opening of the rotating member and the axis of the opening of the corresponding objective optical system are coaxial with each other. Accordingly, the above-mentioned centering and adjustment of direction of optical axes are achieved only by adjusting the tolerance in processing of each lens of the eyepiece and the objective optical system, after mounting the eyepiece and the objective optical system in the holding members thereof, so that the adjustment of mounting for each lens is facilitated.
Further, as described above, the opening in which the eyepiece is mounted and the opening in which the objective lens is mounted are formed by abutting the cutting tool while rotating the mounting base. The rotational axis of the mounting base is identical, both when the opening for the eyepiece is formed and when the opening for the objective lens is formed. Accordingly, with respect to each of the left and right telescopic optical systems, the axis lines of each opening readily become coaxial.
The movable optical systems, which are mounted on the connecting portion, are not restricted to correcting a focused image tremble. For example, optical systems for carrying out an inner focus, which are movable along the optical axes of the right and left telescopic optical systems, can be provided on the connecting portion.